Organic peroxides

ABSTRACT

1. AN ORGANIC PEROXIDE NAMELY 6-T-BUTYLPEROXY-2,6-DIMETHYL-2-HEPTEN-4-ONE.

United States Patent 3,842,129 ORGANIC PEROXIDES Yun Ger Chang andPhilip S. Bailey, Austin, Tex., as-

signors to Reichhold Chemicals, Inc., White Plains,

No Drawing. Original application Aug. 10, 1971, Ser. No. 170,621, nowPatent No. 3,755,454, dated Aug. 28, 1973. Divided and this applicationNov. 29, 1972, Ser. No. 310,560

Int. Cl. C07c 49/04 U.S. Cl. 260-594 2 Claims ABSTRACT OF THE DISCLOSUREThis invention discloses a process of preparing organic peroxides, byreacting a hydroperoxide having the general formula RO-OH with an cp-unsaturated ketone. The 0a,}3-11I'1Sflfi113t6d ketone may have astraight chain structure or a cyclic structure. Reaction takes place ata temperature from about 0 C.-8 0 C. in the presence of an acidiccatalyst. The mole ratios of the components may vary from about 10:1 to1:10.

wherein, R is either an alkyl or an aralkyl group; R R and R are thesame or different members of the group consisting of hydrogen, alkyl,aralkyl, cycloalkyl, alkenyl, cycloalkenyl, aryl, alkaryl groups; R, isa member of the group consisting of alkyl, aralkyl, cycloalkyl, aryl,alkaryl, vinyl and substituted vinyl groups.

Some of these peroxides may be shown by one of the following twoformulas:

and

wherein, R, R and R have the same meanings as mentioned in the precedingparagraph; A is a hydrocarbon group containing two to three carbon atomsin the main chain, of which one terminal carbon atom connects with thecarbonyl group and the other with the beta carbon atom of the np-unsaturated ketones to form a ring, and may be an aliphatic,cycloaliphatic, substituted aliphatic,

aromatic or substituted aromatic group; and B is a hydrocarbon groupcontaining three to five carbon atoms in the main chain which forms aring with the a,fi-unsatu rated system by connecting the carbonyl groupwith one of its terminal carbon atoms and the alpha carbon atom with theother, and may be an aliphatic, cycloaliphatic or substituted aliphaticgroup.

It has been known for a long time that i-unsaturated carbonyl compoundscould be converted into the corresponding epoxides by treatment withhydrogen peroxide in a basic medium. Similarly, it was reported in theliterature that hydroperoxides could convert a,fi-unsaturated carbonylcompounds into the corresponding epoxides in the presence of a base.Harman, U.S. 2,508,256 (1950), reported that addition of hydroperoxideto an n p-unsaturated system containing a polar, meta-directing group,conjugate to the multiple bond, in a basic medium, producing a peroxide.The meta-directing groups include the CH0, COOH, COO(alkyl), COO(metal),CN, CCl N0 SO H, S0 CONH COCOO-H, CO(alkyl) and the like groups. Later,Yang and Finnegan, J. Am. Chem. Soc., 80, 5845 (1958), found that thebase-catalyzed reactions between hydroperoxides, and a,B-unsaturatedsystems gave, instead of peroxides, only the cor-responding epoxides, inyields of 50-90%. The reaction involves the addition of an alkyl peroxyanion to the beta carbon of the activated double bond and theelimination of an alkoxy anion with the formation of the epoxide. If theintermediate anion combines with a proton before the formation ofepoxide occurs, a peroxy addition product is formed. It is apparent thatin a basic medium, the intermediate anion does not have the chance toacquire a proton and, consequently, the final product is an epoxide. Themechanism of the base-catalyzed reaction can be shown as follows:

wherein R is either an alkyl or an aralkyl group.

It is an object of the present invention to produce peroxides by theaddition of hydroperoxides to cap-um saturated ketones.

It is another object of the present invention to provide some novelperoxides which are highly efiicient polymerization initiators andcross-linking agents.

It is still another object of this invention to provide highly efficientmethods for the preparation of such polymerization initiators andcross-linking agents.

These and other objects and advantages of the present invention will'become more apparent from the following description.

It has been found that these objectives can be attained by reacting0a,}9-I1I1Sfltll1'3t6d ketones with hydroperoxides in the presence of acatalyst. The reaction may take place in a solvent or without a solvent.It has been found that hydrocarbons such as pentane, hexane, heptane andbenzene; alcohols such as isopropanol, butanol; ethers such as dioxane;esters such as butyl acetate, methyl butyrate; may be used as solvents.In the case where no solvent was used, the addition reaction becamesomewhat violent, as evidenced by the heat evolved.

In the present invention, the catalyst for the addition reaction ofhydroperoxides to u,B-unsaturated ketones is an acid, such as sulfuricacid, hydrochloric aciid, perchloric acid, nitric acid or phosphoricacid. The use of acidic catalysts in the addition reaction is verysignificant,

since it leads to the formation of peroxides as the final additionproducts, without producing epoxides. The amount of the catalyst usedfor the addition reaction may vary from a trace to about 30%, based onthe total weight of the reactants described below. Usually, the amountranging from about 5% to about 15%, based on the total weight of thereactants, is preferred.

In the reactions of the present invention, the mole ratio oftip-unsaturated ketone to hydroperoxide may vary widely, for example,from about 10:1 to 1:10. The preferred mole ratio of a,,6-unsaturatedketone to hydroperoxide is about 1:1 to 1:2.

The reaction temperature of this invention may range from about C. toabout 80 C. However, the preferred reaction temperature is in the rangeof about 25 C. to about 35 C., on account of the outstanding resultsobtained therefrom. At relatively high temperatures, some side-reactionscould take place. For example, when mesityl oxide was reacted witht-butyl hydroperoxide at 50 C. in the presence of sulfuric acid, theproduct was a mixture of about 50% of di-t-butyl peroxide and about 50%of the desired addition product.

In many cases, the active oxygen contents of the new peroxides of thepresent invention, as determined by the hydriodic acid-sodiumthiosulfate titration method, were lower than the theoretical values.This is probably due to failure of the analytical method in the case ofthis particular type of peroxide.

The hydroperoxides employed as reactants in this invention may berepresented by the general formula wherein, R is either an alkyl or anaralkyl group. Preferably, these are tertiary hydroperoxides, such ast-butyl hydroperoxide, t-amyl hydroperoxide and cumene hydroperoxide.

The u,;8-unsaturated ketones used in this invention may have a straightchain structure or a cyclic structure. They can be represented by one ofthe following formulas:

wherein, R R R R A and B are as previously described for the structuresof the corresponding peroxides.

Because of the strong electron-withdrawing action of the carbonyl group,the olefinic double bond of ogB-ul'lsaturated ketone is electrophilicrather than nucleophilic. Consequently, in the reactions between OB-unsaturated ketones and hydroperoxides, in acidic medium, the initialattack on the olefinic carbon atom is nucleophilic. The mechanisms ofthese acid-catalyzed addition reactions are illustrated as follows:

When hydrocarbon groups, instead of hydrogen atoms, are attached tothebeta olefinic carbon atoms, the reaction between O B-unsaturated ketonesand hydroperoxides does not go further than the addition ofhydroperoxide to the olefinic double bond. The carbonyl group does notreact with hydroperoxide since the infra-red spectra of the peroxidicaddition products show a strong bond due to the non-conjugated carbonylgroup. Presumably, the limited reaction is due to steric efiects. Thehydrocarbon group and the bulky alkylperoxy group attached to the betacarbon atom prevent the hydroperoxide from reacting with the carbonylgroup. In case of phorone, not only the carbonyl group but also one ofthe two carbon-carbon double bonds did not react with hydroperoxide,pre- 15 sumably due to steric hindrance.

The new peroxides of this invention have been found to provide highlyefficient initiators in polymerization reactions, such as thepolymerization of styrene, vinyl esters, alkyl methacrylates and thelike. These peroxides have also been found to be good cross-linkingagents for polyethylene, polypropylene and the like.

Some of the representative preparatory reactions are illustrated by thefollowing equations:

EQUATION (1) (1113 (EH; H (3H HaC-O=CH?|JCH3 HOO-O-CH; H C-F-CHz-[C-CH;

0 CH3 O 5 HaC-J-CH; 4 (3H3 Mesityl oxide t-Butyl 4-t-Butylperoxy-4-hydroperoxide methyl-2-pentanone EQUATION (2) CH CH3 (3H H HCC=OH-C--OH=COH3 HOO-C-OH: 41H.

Phorone CH 0 C 3 HaC(:?CHz("]-CH=( 3CHa f O H3C(|3-CH3 C a6-t-Buty1per0xy-2,6-dimethyl-2- heptent-oue.

EQUATION (3) E30 on, H O on, mo e- 0H, (3H H HQCQCLCHZ HaC-C=CHC=O H00-C-CH1 H;C-CCHZC=O Isophorone C IH; J,

HsC-C-CH: (1H,

3-t-Butylperoxy-3,5,5- 7 trimethylcyclohexanoue EQUATION (4) Thefollowing examples will illustrate the process of preparing the newperoxides of this invention. It is understood, however, that theexamples are for purposes of illustrating the invention and are notintended as limitations thereto.

EXAMPLE 1 Preparation of 4-5-butylperoxy-4-methyI-Z-pentanone Fortygrams (0.40 mole) of 90% t-butyl hydroperoxide, 28.00 grams (0.20 mole)of 70% sulfuric acid and 200 ml. of hexane were mixed together in abeaker. To the resulting mixture, at room temperature, was slowly added19.63 grams (0.20 mole) of mesityl oxide, with agitation. The reactionmixture was stirred at room temperature for five hours longer and thenallowed to stand overnight.

The organic layer was separated, washed five times with -ml. portions of5% potassium hydroxide solution and three times with water and finallydried over anhydrous magnesium sulfate. Filtration and removal ofsolvent under reduced pressure using a water aspirator and a rotatingevaporator left a light-brown liquid weighing 23.80 grams. Thisindicated a yield of 64.40%, based on the amount of mesityl oxide usedfor the reaction. The crude product contained no hydroperoxide shown bylead tetra-acetate test, and had a 7.10% active oxygen content. Afterpurification by two distillations at 55 C. and 0.7 mm., the colorlessliquid product contained 5.74% active oxygen (theoretically, 8.50%)determined by hydriodic acid-sodium thiosulfate titration. Otherconstants obtained for this new peroxide were (1 0.9370, 1 1.4288, MR(calcd) 52.64. MR (obsd.) 51.83.

Analysis.-Calcd. for C H O C, 63.79; H, 10.71; 0, 25.50; molecularweight 188. Found: C, 63.80; H, 10.39; 0, 26.06; molecular Weight 234.

The infra-red spectrum of this compound showed a very strong and sharpband at 1700 cm? due to nonconjugated carbonyl groups, a very strong'band at 1360 cm? with a shoulder at 1372 cm. due to t-butyl groups anda strong band at 870 cm." representing the peroxide groups.

On the basis of the analytical data and the information obtained fromthe infra-red spectrum, the structure of this new peroxide is assignedas follows.

Ha C

The procedure of Example 1 was repeated without using an organicsolventrA cooling bath was employed to keep the reaction temperature at25 C. to 35 C. The product was extracted with ether. The ether solutionwas washed with water and dried over anhydrous magnesium sulfate. Thefinal product was identified as 4-t-butylperoxy-4-methyl-2-pentanone.

EXAMPLE 3 Preparation of 4-t-amylperoxy-4-methyl-2-pentanone In abeaker, 10.4 grams (0.1 mole) of t-amyl hydro peroxide and 14.0 grams'(0.1 'mole) of 70% sulfuric acid were mixed with 100 ml. of hexane. Tothe resulting mixture was added 9.8 grams (0.1 mole) of mesityl oxide,at room temperature, with stirring. The reaction mixture was stirred atroom temperature for five hours and then allowed to stand overnight. Theorganic layer was separated and washed five times with IO-ml. portionsof 5% sodium hydroxide solution and twice with water. Finally, it wasdried over anhydrous magnesium sulfate. Filtration and removal ofsolvent under reduced pressure gave a liquid peroxidic product. It wasidentified as the addition product,4-t-amylperoxy-4-methyl-2-pent-anone.

EXAMPLE 4 Preparation of 4-cumylperoxy-4-methyI-Z-pentanone To 100 -ml.of hexane were added 15.2 grams (0.1 mole) of cumene hydroperoxide and14.0 grams (0.1 mole) of 70% sulfuric acid. To the resulting mixture wasadded 9.8 grams (0.1 mole) of mesityl oxide, at room temperature, withagitation. The reaction mixture was stirred, at room temperature, forfive hours and then allowed to stand overnight. The organic layer wasseparated and washed five times with 10-ml. portions of 5% sodiumhydroxide solution and twice with water. After being dried overanhydrous magnesium sulfate, the solvent was removed under reducedpressure. A liquid was obtained and identified as the addition product,4-cumylperoxy-4-methyl-2-pentanone.

EXAMPLE 5 Preparation of 6-t-butylperoxy-2,6-dimethyl-2-hepten-4- one Ina 500-ml. round-bottom flask, 25.0 grams (0.25 mole) of t-butylhydroperoxide, 14.0 grams (0.1 mole) of 70% sulfuric acid and 200 ml. ofhexane were mixed together. To the resulting mixture was added 9.4 grams(0.068 mole) of phorone, at room temperature, with stirring. Thereaction mixture was stirred at room temperature for twenty-four hoursand at 50 C. for twenty-four hours longer. The mixture was diluted with30 ml. of water. The organic layer was separated, washed ten times with10m]. portions of 5% potassium hydroxide solution and three times with20-m1. portions of water, and finally dried over anhydrous magnesiumsulfate. Filtration and removal of solvent under reduced pressure left abrown liquid weighing 16.0 grams, indicating a yield based on the amountof phorone used for the reaction. The crude product contained nohydroperoxide shown by lead tetra-acetate test, and had a 7.81% activeoxygen content determined by hydriodic acid-sodium thiosulfate method.After purification by distillations at 78-79" C. and 1.5 mm., the paleyellow liquid contained 6.40% active oxygen (theoretically 7.01%), andhad d 0.9950, v 1.4494.

Analysis.Calcd. for C H O C, 68.39; H, 10.59; 0, 21.02; molecular weight228. Found: C, 67.64; H, 10.29; 0, 21.85; molecular weight 240.

The infra-red spectrum of this compound showed a band at 1672 cm.- dueto conjugated carbonyl groups, a strong band at 1600 cm." due to C=CH--groups, a strong 'band at 1360 cm.- with a shoulder at 1373 cm.-indicating t-butyl groups, and a strong band at 864 cm." representingperoxide groups.

Based on these data, this new compound is the peroxidic addition producthaving the following structure.

EXAMPLE 6 Preparation of 6-t-amylperoxy-2,6-dimethyl-2-hepten-4- one Toa mixture of 4.86 grams (0.045 mole) of t-amyl hydroperoxide, 4.20 grams(0.03 mole) of 70% sulfuric acid and 50 ml. of hexane, was added 4.14grams (0.03 mole) of phorone, at room temperature with agitation. Thereaction mixture was stirred at 40'50 C. for fortyeight hours, and thendiluted with 10 ml. of water. The organic layer was separated, washedten times with 5-ml. portions of 5% sodium hydroxide solution and threetimes with l-ml. portions of water, and finally dried over anhydrousmagnesium sulfate. Filtration and removal of low-boiling materials underreduced pressure gave a lightbrown liquid, identified as the additionproduct 6-t-amylperoxy-2,6-dimethyl-2-hepten-4-one.

EXAMPLE 7 Preparation of 6-cumylperoxy-2,6'dimethyl-2-hepten-4- one To amixture of 6.84 grams (0.045 mole) of cumene hydroperoxide, 4.20 grams(0.03 mole) of 70% sulfuric acid and 50 ml. of hexane, was added 4.14grams (0.03 mole) of phorone, at room temperature, with stirring. Thereaction mixture was stirred at 40-50 C. for forty-eight hours. It wasdiluted with 10 ml. of water. The organic layer was separated, washedten times with S-ml. portions of 5% sodium hydroxide solution and threetimes with -ml. portions of water, and then dried over anhydrousmagnesium sulfate. Filtration and removal of low-boiling materials underreduced pressure left a light-brown liquid, identified as the additionproduct 6-cumylperoXy-2,6-di methyl-2-hepten-4-one.

EXAMPLE 8 Preparation of 3-t-butylpheroxy-3,5,5-trimethylcyclohexanoneTo a mixture of 30.0 grams (0.3 mole) of 90% t-butyl hydroperoxide, 14.0grams (0.1 mole) of 70% sulfuric acid and 200 ml. of hexane, was added13.8 grams (0.1 mole) of isophorone, at room temperature, withagitation. The reaction mixture was stirred, at room temperature, forfive hours and then allowed to stand overnight.

' The organic layer was separated, washed twice with 50- ml. portions ofsaturated sodium bicarbonate solution and twice with water, and finallydried over anhydrous magnesium sulfate. Filtration and removal oflow-boling materials under reduced pressure gave a light-brown liquid,weighing 23.4 grams. The product was purified by five distillations at65-67 C. and 1.0 mm. The purified liquid contained no hydroperoxide andhad a refractive index 1 1.4450. The infra-red spectrum of this compoundshowed a strong band at 1725 cm. due to non-conjugated cyclic carbonylgroups; a strong band at 1370 cm:- due to CCH and C(CH groups; and astrong band at 87 8 cm.- due to peroxide groups. The active oxygencontent of this compound determined by hydriodic acidsodium thiosulfatetitration method seemed higher than the theoretical value.

According to these data, it is reasonable to assign the followingstructure for this compound.

Hac C EXAMPLE 9 The preparation described in Example 8 was carried outwithout using organic solvent. The isophorone was mixed with the t-butylhydroperoxide. To the resulting mixture was slowly added the sulfuricacid at room temperature. The reaction mixture was stirred for thirtyhours while the temperature was kept at 25-30 C., using a cold waterbath. The reaction mixture was diluted with water. The organic layer wasseparated, washed with sodium bicarbonate solution and with water, andfinally dried over anhydrous magnesium sulfate. The final product wasidentified as 3-t-butylperoxy-3,5,5 trimethyl-cyclohexanone.

EXAMPLE 10 Preparation of 3-5-amylperoxy-3,5,5-trimethylcyclohexanone Toa mixture of 6.24 grams (0.06 mole) of t-amyl hydroperoxide, 4.20 grams(0.03 mole) of 70% sulfuric acid and 30 ml. of hexane, was added 4.14grams (0.03 mole) of isophorone, at room temperature, with stirring. Thereaction mixture was stirred at room temperature for five hours, andthen allowed to stand overnight. The organic layer was separated, washedtwice with 10-ml. portions of saturated sodium bicarbonate solution andtwice with l0-ml. portions of water, and finally dried over anhydrousmagnesium sulfate. Filtration and removal of low-boiling materials underreduced pressure left a liquid product, identified as the additionproduct, 3-t-amylperoxy-3,5,S-trimethyl-cyclohexanone.

EXAMPLE 1 1 Preparation of 3-cumylperoxy-3,5,S-trimethylcyclohexanone Toa mixture of 9.12 grams (0.06 mole) of cumene hydroperoxide, 4.20 grams(0.03 mole) of 70% sulfuric acid, and 40 ml. of hexane was added 4.14grams (0.03 mole) of isophorone, at room temperature, with agitation.The reaction mixture was stirred at room temperature for five hours, andthen allowed to stand overnight. The organic layer was separated. It waswashed twice with 10-ml. portions of saturated sodium bicarbonatesolution and twice with water, and finally dried over anhydrousmagnesium sulfate. Filtration and removal of low-boiling materials underreduced pressure gave a liquid product, identified as the additionproduct, 3-cumylperoxy-3,5,5-trimethylcyclohexanone.

EXAMPLE 12 Preparation of 2-(l-t-butylperoxy-l-methylethyl)-S-methylcyclohexanone To a mixture of 6.0 grams (0.06 mole) of t butylhydroperoxide, 4.20 grams (0.03 mole) of 70% sulfuric acid, and 40 ml.of hexane, was added 4.56 grams (0.03 mole) of pulegone, at roomtemperature, with stirring. The reaction mixture was stirred, at roomtemperature, for five hours and then allowed to stand overnight. Theorganic layer was separated, washed twice with 20-ml. portions ofsaturated sodium bicarbonate solution and twice with 20-ml. portions ofwater, and finally dried over anhydrous magnesiumsulfate. Filtration andremoval of low-boiling materials under reduced pressure left a liquidproduct, identified as the product, having the following structure.

The invention in its broader aspects is not limited to the specificsteps, methods, and compositions described, but departures may be madetherefrom within the scope of the accompanying claims Without departingfrom the 10 What is claimed is: 1. An organic peroxide namely6-t-butylperoxy-2,6-dimethyl-2-hepten-4-one.

2. An organic peroxide namely6-t-amylperoxy-2,6-dimethyl-2-hepten-4-one.

addition Morrison et 211.: Organic Chemistry 2nd edition, Allyn andBacon Inc., Boston (1966), pp. 967-69.

1;) BERNARD HELFIN, Primary Examiner J. H. REAMER, Assistant Examinerprinciples of the invention and without sacrificing its chiefadvantages.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION 3,842,129 DatedDecember 17, 1974 Patent No Inventor(s) Yun Ger Chang and Bhilip s.Bailey It is certified that error appears in the above-identified patentand that said Letters Patent are hereby corrected as shown below:

Patent No. 3,842,129 should be corrected to show that the originalfiling date was August 21, 1968, which is the filing date of Serial. No.754,572, now abandoned, of which Serial No. 170,621 is a division.

Signed and sealed this 6th day of May 1975.

(SEAL) Attest:

C. MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officerand Trademarks FORM powso USCOMM-DC 60376-P69 Q ".5 GOVERNMENT PRINTINGOFFICE 2 1,, 0-3C-SSI,

1. AN ORGANIC PEROXIDE NAMELY6-T-BUTYLPEROXY-2,6-DIMETHYL-2-HEPTEN-4-ONE.